1. Field
One embodiment of the invention relates to a storage device using a nonvolatile flash memory and a control method thereof, and the storage device is configured to be able to realize the fastest response speed with which notice of a data write command (write command) received from a host device having been executed is given to the host device.
2. Description of the Related Art
In recent years, a storage device on which both of a memory card which is a semiconductor storage medium and a hard disk (HD) drive using a hard disk which is a magnetic storage medium can be mounted is developed (refer to Jpn. Pat. Appln. KOKAI Publication No. 2004-055102). For example, data of the memory card fetched from the exterior can be backed up into the hard disk (HD) which is a magnetic storage medium. Further, data of a hard disk (HD) can be transferred to the memory card and can be thus taken out.
As a mobile storage device, a storage device using a flash memory is developed (refer to Japanese Patent Publication No. 3407317). A large number of errors occur in the flash memory when the number of erase operations of the flash memory becomes large (for example, 100,000 times), and therefore, an attempt is made to solve the above problem. For example, a data management method for suppressing the number of erase operations for a specified area from becoming larger is provided.
As described above, there are devices using a plurality of various types of recording media. However, when data including a write command has been supplied from the host device, it is important to determine into which recording medium the data can be written. A method of selecting a recording medium as a write destination has much influence on the overall data processing speed.